from PySide6.QtCore import Qt
from PySide6.QtWidgets import QApplication, QMainWindow, QPushButton, QWidget

import sys

class ButtonHolder(QMainWindow):
    def __init__(self) -> None:
        super().__init__()
        self.setWindowTitle("ButtonHolder Window")
        button = QPushButton("Press me")

        self.setCentralWidget(button)


app = QApplication(sys.argv)

window = ButtonHolder()
window.show()

app.exec()